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Non-uniform contact pressure with non-matching surface mesh

Creator
Creator

FEMAP / Nx Experts,

 

I'm a new FEMAP / Nx Nastran user, and I'm looking for some help. I've been running some simple interferance analysis cases. During one of my cases I hurried and accidently did not have a mesh that was matching on the master and slave surfaces. This mesh model produced some really ugly contact pressures and rough stress results. Does anyone have any tricks or techniques for smoothing the contact pressures of surfaces that do not have a matching mesh? To illastrate what I am seeing I've made a simple model in FEMAP / Nx Nastran, the mesh on the outer hoop is uniformly hex meshed and the mesh on the inner bar is purposely Tetrahedral meshed. The resulting contact pressure is not very uniform. I've uploaded some pictures to illustrate the issue I'm trying to discribe. The first image show the FEMAP / Nx results with a matching mesh, the second picture show the FEMAP / Nx results with a non matching hex and tet mesh, the third image is from ANSYS with a non matching hex and tet mesh. If anyone has worked through this issue in the past I would be curious to know how it can be resolved.

 

Thank you for your time.

 

JP

3 REPLIES

Re: Non-uniform contact pressure with non-matching surface mesh

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom

Dear John,

This is the typical issue "of non desired initial penetrations" when dealing with contacts, take a look to my block where I explain the problem:

 

https://iberisa.wordpress.com/2012/01/14/mejora-de-resultados-de-contacto-lineal-con-inipene-en-fema...

 

not desired penetrations

 

initial penetration

 

Best regards,

Blas.

Blas Molero Hidalgo, Ingeniero Industrial, Director
IBERISA • 48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog Femap-NX Nastran: http://iberisa.wordpress.com/

Re: Non-uniform contact pressure with non-matching surface mesh

Creator
Creator

Dear Blas,

 

Thank you again for the wonderful information! This is exactly what I was looking for with my FEA model. In case anyone else is interested the IPINPENE commands also work with offset contact surfaces. 

 

Thank you for all of your help!

 

JP

Re: Non-uniform contact pressure with non-matching surface mesh

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom

Dear John,

I am happy to be of help!. To learn more about the use of OFFSET in contacts take a look to my post:

https://iberisa.wordpress.com/2012/01/16/tratado-completo-sobre-como-resolver-problemas-lineales-de-...

 

offset

 

Best regards,

Blas.

Blas Molero Hidalgo, Ingeniero Industrial, Director
IBERISA • 48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog Femap-NX Nastran: http://iberisa.wordpress.com/